This invention relates, in general, to making solid-state sensors, and more specifically to making micromachined cantilever beams for sensors.
Cantilever beam structures have been generally used in electronic sensors to detect movement. Movement of the sensor causes the cantilever beam to bend. Two methods that have been commonly used to detect bending of micromachined structures are piezo-resistive and capacitive structures. The piezo-resistive method uses a resistor network which changes resistance as the structure bends. The capacitive method uses a fixed plate mounted in parallel with and in close proximity to a moving plate. As the moving plate bends, and gets closer or farther away from the fixed plate, a change in capacitance occurs.
Conventional cantilever piezo-resistive and capacitive devices however, have several problems such as, fragility, poor deflection or movement of the beam, and long term reliability.
Commonly designed cantilever beams are very sensitive to extreme and sudden movements or the like. Damage occurs to the cantilever beam when movement occurs that is outside the operating range of the device. Once the damage occurs the device is useless.
Poor deflection or movement of the cantilever beam in response to movement has also been a problem in conventionally designed structures. The poor deflection of the cantilever beam structure is due to stiffness or rigidity of the conventional designs for cantilever beams. Accordingly, it would be desirable to provide a sensor structure that has cantilever beams which overcome the aforesaid problems.